Project Summary/Abstract Our long-term goal is to develop effective physical rehabilitation approaches to improve mobility and prevent falls in people with Parkinson?s disease (PD). To reach this goal, the purpose of our proposal is to identify objective measures of turning, gait and mobility activity during daily life that best reflect fall risk and to explore the use of daily life monitoring of mobility as outcome measures for rehabilitation to improve turning quality. Quantification of turning ability with new technology involving body-worn, inertial sensors could provide powerful, new outcomes for clinical trials and clinical practice focused on mobility disability. We hypothesize that objective measures of turning will best discriminate fallers versus nonfallers, predict falls in people with PD without a fall history, and turning can be improved with rehabilitation in PD. Two cross-sectional studies will determine the usefulness of innovative, objective measures of turning, gait, and activity over 7 days of daily living with body-worn inertial sensors for use in rehabilitation. Aim I is a retrospective, observational, study comparing turning, gait, and activity with body-worn sensors in people with PD with and without a history of falls in the previous 12 months. Aim II is a prospective study, only in the nonfallers, investigating the best set of measures of mobility during daily life to predict the first falls in the 12 months after 7 days of daily life monitoring. Aim III is an exploratory, randomized, exercise intervention study to plan a future clinical trial for improving turning in daily life. Specifically, the fallers collected in Aim I will be randomized into a novel, 6-week, Turning Boot Camp group or an Active Control Strengthening) group. This study is designed to advance healthcare of people with PD by improving their mobility function and the quality of their lives by developing more effective rehabilitation for mobility disability. Balance and gait disorders affect most people with chronic disease or neurological disease, resulting in inability to control a critical balance task ? quickly change walking direction (turning). This proposal will improve our understanding of the contribution of turning impairments during community living to falls and parkinsonian impairments and explore whether rehabilitation can improve quality of turning for functional mobility in daily life. Based on these studies, clinicians will be able to use body-worn sensors to quickly and accurately assess quality of turning and implement a novel Turning Boot Camp program focused on improving mobility disability.